1. Field
Example embodiments relate to an MXene nanosheet and a manufacturing method thereof.
2. Description of the Related Art
Graphene is a single atomic layer of a honeycomb structure, which is composed of carbon atoms, and has received much attention worldwide due to its desirable physical properties. Recently, the explosive studies on graphene have sparked new interests towards graphene-analogous two-dimensional materials.
One of the two-dimensional materials, MAX phase (wherein M is a transition metal, A is an element of Group 13 or 14, and X is carbon and/or nitrogen) is a crystal composed of MX which has a semi-ceramic property and A which is a metal element different from M, and has desirable physical properties, e.g., electrical conductivity, oxidation-resistance, mechanical processability, etc. Until now, there have been over 60 synthetic MAX phases.
MAX phase is a two-dimensional material, but the transition metal carbide layers are stacked by relatively weak chemical bonding between A element and the transition metal M, unlike graphite or dichalcogenide. Therefore, modifying the two-dimensional structure using a general mechanical or chemical exfoliation method may be difficult.
In 2011, three-dimensional titanium-aluminum carbide was changed into a completely different two-dimensional structure by selectively removing aluminum layers using hydrofluoric acid. The research team called this two-dimensional material “MXene”, which is obtained by exfoliation of the MAX phase. MXene has electrical conductivity and strength similar to those of graphene, and has a broad range of applications, ranging from energy storage devices to biomedical applications and composites.
However, because A layers are removed by exfoliating the MAX phase under relatively strong acid conditions, the exfoliated MXene is terminated with surface functional groups, e.g., O, OH or F, binding to the transition metal M, and such surface modification of the functional group is assumed to cause deterioration of intrinsic properties of MXene.